I can understand your point and this platform could really win with some more big project if some companies took it more seriously, like on other social media.
In my opinion, the real problem is not a matter of bringing them all, but make steemit part of their initial choice when they share.
It is even desirable that companies can continue to share in reddit, medium and others. It should not be a matter of 'fighting' to see which platform is the best, since they have totally different readers and audiences. The goal should always focus on providing and adding value to the project in order to spread the message as best it can to grow and thrive independently of the chosen medium.
I think that with time and the growth of the steemit platform that will happen sooner or later. However, as with all successful networks and social media, the platform must first focus on attracting the masses and when they are consolidated, only then companies start looking at these media as serious ways of capitalizing on and sharing large projects.